Aluminium chlorohydrate is an aluminium salt formed from aluminum or aluminum hydroxide, hydrochloric acid, and water, and optionally also including zirconium and/or complexing agents such as amino acids or polyols. Such salts are used in deodorants and antiperspirants, and as coagulants or flocculants in water purification processes. In aqueous solution, these salts form complex substructures, e.g., Al13 units with a Keggin ion structure, which in turn form larger polymeric species with molecular weights (MW) of over 1000 Daltons. The precise ratios of elements in these salts and the precise three dimensional structures formed can be controlled by method of manufacture. Typically, aluminum chlorohydrate salts may have the general formula AlnCl(3n-m)(OH)m, e.g., Al2Cl(OH)5 or Al4Cl2(OH)10. These salts may additionally be in complex with zirconium and/or an amino acid, ammonium acid, or a polyol, e.g., Al/Zr tetrachlorohydrex-Gly ([Al4Cl2(OH)10 ZrOCl2]NH2CH2COOH).
Size exclusion chromatography (“SEC”) or gel permeation chromatography (“GPC”) provides information on polymer distribution of aluminum chlorohydrate in aqueous solutions. Distinctive peaks have been identified, corresponding to different size populations of the polymer complexes in solution, appearing in a chromatogram as peaks 1, 2, 3, 4 and a peak known as “5,6”. Peak 1 is the larger species (greater than 60 Angstroms), generally observed only in salts with zirconium. Peaks 2 and 3 are larger aluminum species. Peak 4 is a smaller aluminum species (aluminum oligomers or small aluminum cluster). Peak 5, 6 is the smallest aluminum species.
There remains a need for aluminum chlorohydrate salts exhibiting a high SEC Peak 1.